Cancer happens when certain cells in our body start to grow abnormally.
The division of cells is normally very well-controlled by sophisticated systems in the body; many of them are built within the cell itself. But when this control is lost, cells grow and create lumps. If the lump grows, it can eventually ‘invade’ nearby organs, blood vessels and nerves. This lump is called a tumor and a tumor that continues to grow is what medicine calls ‘cancer’.
Cancer cells may spread through the blood or lymphatic system, to organs like the lungs, bones, liver and brain. There is no body organ immune against cancer. Some cancers do not form tumors, but rather they grow in the blood and bone marrow (where blood cells are created). These are called leukemias and they can make a person ill very rapidly (acute) or may linger for a longer period of time before a person becomes very ill (chronic). Similarly, some cancers grow from cells that usually reside in lymph nodes and may spread to other lymph nodes. These cancers are called lymphomas.